The Red Sox have yet to extend an offer to free-agent reliever Jonathan Papelbon, according to a Major League source. Papelbon is eligible to become a free agent this week once Boston's exclusive negotiating period ends. He is expected to be one of four top tier closers on the free agent market, joining Francisco Rodriguez, Heath Bell, and Ryan Madson. Papelbon, 30, made $12 million in 2011, having agreed to a one-year deal in his final year of being arbitration eligible.